Naturally occurring diamonds have been used as jewellery for many centuries, and each diamond is formed throughout the history and evolution of the Earth, and thus all are unique by nature.
Although there exist many rules or grading systems in judging and assessing the quality of a unique piece or gemstone, it can be difficult to assess the difference between two diamonds or gemstones having similar grading. Thus there exists an importance to allow the marking of a diamond gemstone so as to provide a unique marking to each diamond or gemstone to allow ease of identification and hence tracing.
In gemstone identification and diamond quality grading and analysis, observation and evaluation from a top view normal to the top surface of gemstone or diamond provide relevant evidence and information pertaining to clarity and cut as certified in reports by international standards laboratories including GIA (Gemological Institute of America Inc.), IGI (International Gemological Institute), Gem-A (The Gemmeological Association of Great Britain), NGTC (National Gemstone Testing Center, China) and the like.
From a customer standpoint, parameters such as for a diamond, a flashing brightness often utilizing termed such as “brilliance” (the total amount of light that is reflected by a diamond) or “fire” (the dispersion of light into different colors of light), which are typically observed or admired from a top surface as well as from the top table of a diamond, may be utilised.
It is important parameters of gemstones or diamonds, such as those indicative of the quality, grade, cut, origin, be associated with a gemstone or diamond, for both commercial and security purposes.
Due to the value of a diamond or precious stone varying significantly, and due to the event of theft and counterfeiting thereof, marking should be performed in a manner so that a diamond or precious stone may be identified by a unique identification mark which is indicative of the said diamond or gemstone. Such identification may be utilised for association with known parameters of said diamond or gemstone.
Within the prior art, there exist two main techniques for marking the gemstones and diamonds, these being:                (i) laser marking, and        (ii) FIB (Focused Ion Beam) marking.        
For laser marking, this technique is limited by the laser spot size, which typically cannot be utilised for generating fine patterns on diamond surface. The mechanism of laser marking is that the laser energy is absorbed when the laser beam reaches the diamond surface, whereby a portion of the diamond is ablated, leaving a marking that follows the path of a laser beam. Due to the large heat affected zone (HAZ) of laser spot, damage to the diamond may occur from the laser. Although the development of ultra-fast laser offers low pulse energy and high pulse energy density, which result in smaller HAZ, the use of such methods still pose a risk of damage when marking a diamond. Further, the use of such a technique of laser marking does not typically leave a clean surface on a diamond as the ablated surface will result in the formation of graphite irrespective of whether the laser source is excimer laser or picosecond laser or femtosecond laser. Also, in view of the relatively large mark that the laser may form, a resultant darkened mark on the diamond may be quite visible even to the naked eye.
FIB marking, in comparison to laser marking, has several advantages. The spot size is 1000 times smaller than for a laser beam, which makes it possible to mark a surface by writing a higher amount of data. Typically for laser beam marking, it is limited to the formation of some letters, characters and simple logos and the like. The use FIB may allow pictures or representations or Chinese characters, high-resolution brand to be inscribed.